Plasticizer



Patented June 21, 1949 UNITED. STATES PATENT OFFICE.

No Drawing. Application July 22, 1946, Serial No. 685,369

13 Claims. (01. 260-398) This invention relates to plasticizers forsynthetic resins and more particularly to solvent type plasticizers forthermoplastic resins and other resins.

, A principal objective of this invention has been to, produce a good,inexpensive plasticizer for synthetic resins.

By the term synthetic resins we mean those high molecular weightmaterials which are obtained by the polymerization of one or more typesof short chain molecules and we refer particularly to that class ofresins known as thermoplastics, that is, resins which can :be worked andformed under heat or heat and pressure without becoming infusible andinsoluble under these conditions.

In this application the term plasticizer is used to describe a materialwhich may be mixed with a resin to facilitate fabrication and to improvethe characteristics of the finished resin. With many types of resins, aplasticizer is a necessary part and may form a major portion of thefinal. product. The proper choice of plasticizer makes it possible tovary such important properties as flexibility, elasticity, elongation,moldability, and impact resistance.

A familiar type of plasticizer is the solvent type," i. e., aplasticizer which dissolves or substantially dissolves in the resin toform a homogenous, plasticized product. Solvent type plasticizersgreatly improve the flexibility and impact resistance of finishedresins. However, to be satisfactory, a solvent type placticizer must becompatible with the resin to be plasticized, and must not bleed,separate, or evaporate out of solution during the life of the resin, andin addition must sufficiently improve the resin without unduly weakeningits tensile strength and lowering its softening point.

In our copending application, Serial No. 560,198, filed October 24,1944, U. S. Patent 2,474,010, a method is disclosed for disruptivelyoxidizing the nitrile of an unsaturated fatty acid to break the doublebond and produce thereby a mixture of an unsaturated carboxylicaliphatic nitrile and a short chain fatty acid. For example, anunsaturated nitrile is oxidized in a reaction which may be written asfollows:

hydrlc alcohol to form valuable plasticizers. To

illustrate, the mixed products derived from the disruptive oxidation ofan unsaturated nitrile may be esterified with a glycol to form a mixedneutral ester by a reaction which may be written as follows:

R,C01H H0R3-OH Ho,G-R205N Ri O2-Rr-O:C E 28:0 (whereRa is an aliphaticradical and may con tain one or more ethenoxy groups).

Esters may .be disruptively oxidized in the same manner as nitriles, andthe products of oxidation may be esterified with di or polyhydricalcohols,

In either case plasticizers are produced by a similar pair of reactions.The reactions are as follows: where M is a radical which is a member ofthe group consisting of the nitrile and esters of short chain aliphaticalcohols having 1 to 12 carbon atoms, and

is a nitrile or an ester of an unsaturated fatty acid:

During this reaction, other esters are also believed to be formed. Shortchain fatty acids of the formula formed in the oxidation may betransformed into may be formed in the oxidation also form esters bothsingle and mixed.

If desired, the various esters produced may be separated one fromanother by any one of a variety of simple separation methods such assolvent separation or vacuum distillation. Each component of theesteriflcation mixture individually is an excellent plasticizer.However, still more important from a cost viewpoint, the products inadmixture display excellent plasticizing characteristics. Thus we preferto use the esterified product containing a mixture of neutral esters forour plasticizer without the use of any separation steps, except removalof the oxidizing agent, and an excellent plasticizer is made in asimple,

two stage process from an unsaturated aliphatic nitrile or ester and apolyhydric alcohol by (1) disruptively oxidizing the nitrile or ester tobreak' the double bond and (2) esteriiyin the acids produced with a dior polyhydric alcohol;

In the past diesters of short chain fatty acids with dihydric alcoholshave been used as plasticizers. In addition, esters oi. dicarboxylicacids and monohydric alcohols have been used. Both are excellentplasticizers but their preparation entails a number of complicatedsteps. One method of preparation of a dicarboxylic acid is By theoxidation of an unsaturated fatty acid to break the double bond andproduce a mixture 01' a short chain fatty acid and a dicarboxylic acid.The components of this mixture. in turn must be separated beforebeingesterifled and cannot be esterified together because, if a dihydricalcohol is used to esterify the mixture, a linear type polymer is formedwith the dicarboxylic acid while if a monohydric alcohol is used, theshort chain fatty acid forms simple mono-esters, which areunsatisfactory plasticizers from the standpoint of volatility. Themethod of this invention, on the other hand per mlts directesterification of oxidation products, for one of the carboxyl groups ofthe dicarboxylic acid is rendered inactive to esterification by thepresence of the nitrile or ester group; and the mixed oxidation productscan be esterified directly with a dihydric alcohol without danger of theformation of linear polymers.

Our preferred esterification reagent is an aliphatic dihydric alcoholsuch as glycol, diethylene glycol, triethylene glycol, etc. In thisapplication the term dihydric alcohol is intended to include the variousmembers of the ethylene glycol series which contain one or more ethenoxygroups as well as other dihydric alcohols. However, other polyhydricalcohols such as glycerine can also be used to form plasticizers, butthe plasticizers formed, generally speaking, are not as satisfactory asthose produced by esterification with a glycol.

The plasticizers of this invention can be used alone or in combinationwith conventional plasticizers. Various separation and purificationsteps may be added to vary the qualities of the plasticizers producedand to remove unwanted materials.

Typical synthetic resins which can be plasticized with our plasticizersare polyvinyl butyral,

polyvinyl acetate, ethyl cellulose, cellulose acetate butyral, andpolyvinyl chloride. The following examples are given to illustrate, theprinciples of the invention. Various modifications which can be madewill be readily apparent to one skilled in the arts, and the inventionis not intended to be limited except as set forth in the claims. In allof the examples, the proportions are by weight.

Example 1 500 parts of oleonitrile were heated and stirred at atemperature of between 80 centigrade and 90 centigrade with a solutionconsisting of 1900 parts sulphuric acid, 760 parts chromic acid, and

l 3040 parts Water, until the mixture developed a green color andtitration analysis indicated that all the chromic acid had been reduced.The mix- 1 diethylene glycol. The ester not. This intermediate oxidationproduct had an iodine value of 12 and a neutral equivalent of 215. Adiethylene glycol ester was prepared from the oxidation product. using a15 percent excess of productformed had a final acid number of 4.42. v

24 parts of the ester product and 60 parts of polyvinyl chloride werethoroughly mixed and compression molded to give a plasticized, molded,flexible sheet.

Example 2 1000 parts of isobutyl oleate are oxidized with 17,100 partsof a chromic acid solution containing enough chromic acid (1203 parts)to give a 50 per cent excess of the calculated theoretical quantity tocompletely oxidize the ester at the double bond. The composition of thissolution is approximately as follows:

Percent Chromic acid 6.77 Chromic sulphate 13.2 Sulphuric acid 21.9Water 58.1

An oxidizing solution of this composition normally is obtained by plantelectrolytic regeneration of an aqueous chromic sulphate-sulphuric acidsolution to the extent of 50 per cent to 55 per cent of maximumregeneration.

The above volume of oxidizing solution was divided into three parts andemployed in three separate treatments. During each treatment the mixturewas agitated mechanically and maintained at a temperature of betweencentigrade and centigrade. When the chromic acid solution from eachtreatment had become completely spent, as indicated by appearance andtitration analysis, the spent solution was drawn 011.

The oxidized product obtained in this manner was treated with 2 per centby weight concentrated sulphuric acid at 90 centigrade with agitation torid the product of a green coloration. This was followed by suflicientwater washing to free the product of mineral acidity. The mixedoxidation product finally obtained had an iodine value of 215 and was alight colored oil.

800 parts of the oxidized mixture were esterified with 205 parts(theoretical amount) of diethylene glycol in the presence of carbondioxide, which was bubbled through the mixture while it was slowlyheated to a temperature of 250 centigrade. The mixture was heated for 8hours. 20.5 additional parts (10 per cent of theory) diethylene glycolwere added and the mixture was heated for 10 hours further at 250centigrade to give a finished plasticizer which had an acid number of1.9.

Example 3 270 parts of polyvinyl chloride were milled on a rubber millwith 180 parts of the plasticizer produced in Example 2. The sheetformed by milling was put in a press and compression molded at atemperature of centigrade. A clear, straw- Example 4 200 parts of @10per cent solution of polyvinyl butyral (20 parts polyvinyl butyral, 36parts toluol. and 144 parts isopropyl alcohol) were I mixed with 6 partsof the plasticizer produced in Example 2. The mixture was flowed onto aglass sheet. After evaporation of the solvents, a clear, water-whitefilm remained showing complete compatibility.

Example 5 100 parts of polyvinyl acetate and 15 parts of the plasticizerproduced in Example 2 were heater and stirred together at a temperatureof approximately 170 centigrade until thoroughly dispersed. The mixturewas cooled to give a clear yellow ulastic showing no exudation of theplasticizer.

Example 6 200 parts of a solution of ethyl cellulose (14 centipoiseethyl cellulose containing 30 parts ethyl cellulose, 34 parts n-butylalcohol, and 136 parts xylol) were mixed and shaken with 15 parts of theplasticizer produced in Example 2. The mixture was flowed onto a glassplate. After evaporation of the solvents, a clear water-white film ofplasticized ethyl cellulose remained.

Example 7 200 parts of a per cent solution of cellulose acetate butyral(20 parts cellulose acetate butyral, 36 parts methyl acetate, and 144parts methyl cellulose acetate) were stirred with 10 parts of theplasticizer produced in Example 2. The mixture was flowed on a glassplate and gave, after evaporation of the solvents, a clear waterwhitefilm of plasticized resin.

Having described our invention, we claim:

A new composition of matter comprising the mixed ester of an aliphaticdihydric alcohol with a fatty acid and a. carboxylic aliphatic nitrile.

2. A plasticizer comprising the mixed ester of an aliphatic dihydricalcohol with a fatty acid and a carboxylic aliphatic nitrile.

3. A new composition of matter comprising the mixed ester of analiphatic dihydric alcohol with a fatty acid having from 1 to 12 carbonatoms and a carboxylic aliphatic nitrile.

4. A method of forming a plasticizer comprising disruptively oxidizingan unsaturated aliphatic nitrile to break the double bond withoutaffecting the nitrile group and esterifying the oxidation products withan aliphatic dihydric alcohol.

5. A method of forming a plasticizer which comprises disruptivelyoxidizing a compound of the formula to cleave the double bond, in whichR1 and R: are aliphatic radicals and M is a member of the groupconsisting of the nitrile and esters of aliphatic alcohols having 1 to12 carbon atoms, and then esterifying the mixed oxidation products withan aliphatic dihydric alcohol.

6. A new composition of matter which has the 6 f o r m 111 aR1CO2-R3OzCRz-M in which R1 and R2 are aliphatic radicals, M is a memberof the group consisting of the nitrile and esters of aliphatic alcoholshaving 1 to 12 carbon atoms, and R3 is an aliphatic radical residue froman aliphatic dihydric alcohol.

7. A method of forming a plasticizer which comprises disruptivelyoxidizing a member of the group consisting of the nitriles and esters ofmonounsaturated fatty acids to cleave the double bond and thenesterifying the mixed oxidation products with an aliphatic dihydricalcohol.

8. A method of forming a plasticizer which comprises disruptivelyoxidizing a member of the group consisting of the nitrile of oleic acidand esters of oleic acid with aliphatic alcohols having one to twelvecarbon atoms to cleave the double bond and then esterifying the mixedoxidation products with an aliphatic dihydric alcohol.

9. A method of forming a plasticizer which comprises disruptivelyoxidizing an ester of oleic acid and an aliphatic alcohol having one totwelve carbon atoms to cleave the double bond and then esterifying themixed oxidation products with an aliphatic dihydric alcohol.

10. A method of forming a plasticizer which comprises disruptivelyoxidizing an ester of oleic acid and an aliphatic alcohol having threeto four carbon atoms to cleave the double bond, and then esterifying themixed oxidation products with an aliphatic dihydric alcohol.

11. A method of forming a plasticizer which comprises disruptivelyoxidizing an ester of oleic acid and an aliphatic alcohol having fourcarbon atoms to cleave the double bond, and then esterifying the mixedoxidation products with diethylene glycol.

12. A new composition of matter comprising the mixed ester of a dihydricaliphatic alcohol with afatty acid having one to twelve carbon atoms anda half ester of an aliphatic dicarboxylic acid and an aliphatic alcoholhaving one to twelve carbon atoms.

13. A new composition of matter comprising the mixed ester of analiphatic dihydric alcohol with a fatty acid having one to twelve carbonatoms and a half ester of azelaic acid and an aliphatic alcohol havingone to twelve carbon atoms.

LATIMER D. MYERS. J. D. FITZPATRICK.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 0,93 Grofl. June 14, 1938 2,305,03 Osgood Dec. 15, 1942 2,380,061 Moury July 10, 1945

